More expensive than a whole chicken, but easier to deal with, buying a big pack of chicken breasts and then individually freezing them for future use.
Recommending the pasta mentions, make sure it's whole wheat or you're just throwing away money on something that lacks much nutritional quality.
Cook those up and a cheap amazingly delicious sauce to top them with can just be made from canned crushed tomatoes. Add some seasonings (like oregano and basil) and you have a sauce that tastes better than premade jarred sauces at a fraction of the price.
Spices and seasonings are an expensive initial investment but they will last a long time and make up for their initial cost many times over in flavor and the multiple ways you can spice (pun) up your self-made cheapo meals.